This invention relates to a storage and dispensing system for the storage and dispensing of liquids. In particular, the invention relates to a radio frequency identification (RFID) antenna including an intrinsic safety barrier for use in a hazardous liquid dispensing environment.
Certain manufacturing processes require the use of liquid chemicals such as acids, solvents, bases, photoresists, dopants, inorganic, organic and biological solutions, pharmaceuticals, and radioactive chemicals. Storage and dispensing systems allow alternative containers to be used to deliver liquid chemicals to a manufacturing process at a specified time.
These containers include an electric storage device attached to the cap of each container which contains information about the chemical stored inside the container. For example, a radio frequency identification (RFID) tag may be attached to the container, the RFID tag including a place for electric information storage such as an electrically erasable programmable read only memory (EEPROM) and a passive radio frequency (RF) transponder. The information on the RFID tag is typically in communication with an RF antenna to, for example, assure that the proper chemical is being used at the proper time and to access other information on the EEPROM. The RF antenna is typically in electrical communication with a computer via an RF card connected to the computer. For a further description of this information storage system, see Pub. U.S. App. 2002/0189667, to O'Dougherty et al., which is herein incorporated by reference.
At times, chemicals used in manufacturing and production environments are volatile, and must be stored in a controlled hazard area. In order to allow the use of certain electrical equipment and apparatus (such as RFID tags and RF antennas), which could potentially cause ignition of the hazardous substances, consideration must be made for safety and protection against this ignition possibility.
One method of preventing an explosion caused by ignition of the hazardous substances is to make the electrical equipment intrinsically safe. The concept of intrinsic safety in electric process control systems is known in the prior art. Intrinsic safety involves limiting the electrical energy at potential sources of ignition in electrical circuits (hot components and spark sources) to such low levels that even under abnormal (fault) conditions there is no possibility of the electrical energy igniting an explosive atmosphere.
In a liquid storage and dispensing system including volatile liquids, the storage containers must be kept in a hazard area. Conventional systems do not allow for electrical communication with the storage containers in the hazard area. A liquid storage and dispensing system with an intrinsically safe electrical communication system would be an improvement over conventional systems.